276 Cc. JUDSON HERRICK 
brates) come to be one of the dominant exteroceptive systems, 
that is, it functions as a distance receptor. Nevertheless, 
throughout the entire phylogenetic history of this system it 
exhibits pronounced interoceptive or visceral functions associated 
with the selection of food, functions closely similar to those 
of the. gustatory system (Herrick, ’08). In man, a micros- 
matic animal, the sense of taste and the interoceptive aspects 
of the sense of smell are so intimately related that we are unable 
introspectively to separate them, and physiological experimenta- 
tion is required to effect this analysis. One wonders whether, 
if we were provided with a functional vomeronasal organ and 
its specific central apparatus as this is seen in the frog, our sensory 
experience would not thereby be enlarged. : 
VI. SUMMARY 
1. The vomeronasal organ (Jacobson’s organ) first appears 
in Amphibia, apparently in correlation with the opening of the 
posterior nasal aperture. In Urodela it is present (if at all) in 
very rudimentary condition, but in Anura it has assumed defini- 
tive form as a diverticulum from the medial side of the nasal sac 
provided with its specific innervation, the vomeronasal nerve. 
2. The vomeronasal nerve terminates in a specific part of the 
olfactory bulb, the vomeronasal formation, and from the latter 
a specific secondary path, the ventrolateral olfactory tract, 
passes to a differentiated amygdala in the ventrolateral wall of 
the cerebral hemisphere. 
3. The other connections of the anuran amygdala are: with 
the opposite amygdala through the anterior commissure; with the 
adjacent pyriform lobe; with the medial olfactory areas (septum 
and preoptic nucleus) ; with the habenula; and with the hypothal- 
amus. The connection last mentioned is by descending and 
ascending fibers of the olfactory projection tract, which is the 
equivalent of the tractus pallii of fishes. 
4. The frog possesses a true corpus striatum (paleostriatum) 
specifically related with the lateral forebrain bundle and quite 
separate from both the lateral olfactory nucleus and the amyg- 
dala. 
